1. Field of the Invention
The present invention relates to a stereomicroscope capable of providing a stereoscopic image of an object.
2. Description of the Related Art
A stereomicroscope is used for, for example, brain surgery to provide a stereoscopic image of a target. The stereomicroscope has an inlet opening formed at a lower part of the body of the stereomicroscope. The inlet opening receives a flux of light reflected from a target. The light flux passes through an objective system, a zoom system, and an eyepiece system to the eyes of an observer. Usually, the objective and zoom systems are vertically stacked one upon another above a target. The stacked configuration is vertically long to elongate the distance from eyepieces at the top of the stereomicroscope to the inlet opening at the bottom of the stereomicroscope. Due to the long distance to a target, a doctor who sees the target through the stereomicroscope must stretch his or her arms when operating on the target. This deteriorates the doctor""s workability.
To cope with this problem, Hanzawa disclosed a stereomicroscope of new structure in Japanese Unexamined Patent Publication No. 6-138394. This stereomicroscope has objective and zoom systems that are horizontally arranged above a target, to reduce the vertical size of the stereomicroscope. The objective and zoom systems of Hanzawa are each a single system employing large lenses. The objective system is horizontal, and therefore, must employ an optical element at an inlet opening to orthogonally reflect an incoming light flux.
A stereomicroscope is frequently provided with an assistant microscope so that a surgery assistant may observe a target or study surgery techniques. The assistant microscope is in one body with the stereomicroscope, to share objective and zoom systems with the stereomicroscope.
The conventional stereomicroscopes mentioned above usually employ a single zoom system consisting of large lenses that pass two light fluxes through peripheral parts of each lens. Due to the large lenses of the zoom system, an objective system that is contiguous to the zoom system must employ large lenses, too. Since the lenses of the objective system are in the vicinity of an inlet opening for receiving light from a target, the inlet opening must also be large. The large inlet opening hinders a doctor from observing a target under the inlet opening with the naked eye when the doctor shifts his or her eyes from eyepieces of the stereomicroscope. It is frequent that a doctor observes a target alternately with the stereomicroscope and with the naked eye. Thus the stereomicroscope of broad width interferes with the doctor""s sight.
The stereomicroscope with a horizontal objective system must have an additional optical element at an inlet opening to orthogonally reflect a vertical light flux from a target into the objective system. Such an additional optical element involves a curved optical axis to elongate an optical path from a target to the objective system. Accordingly, the inlet opening must be large to observe a wide area at low magnification. The large inlet opening hinders doctor""s sight, increases the number of parts, and complicates the peripheral structure of the inlet opening.
The stereomicroscope with an integrated assistant microscope has a problem of hardly removing the assistant microscope when it is not needed. The assistant microscope shares optical systems with the stereomicroscope, and therefore, it is impossible to separately adjust the magnifications of the assistant microscope and stereomicroscope. This hinders combinational surgery by two doctors with a main doctor using the stereomicroscope to operate on a deep part of a target and an assistant doctor using the assistant microscope to operate on a shallow part of the target.
An object of the present invention is to provide a stereomicroscope of reduced vertical size to enable a doctor to easily observe a target with the naked eye from around eyepieces of the stereomicroscope. The stereomicroscope has an assistant microscope that is easily attached to and detached from the stereomicroscope.
In order to accomplish the object, a first aspect of the present invention provides a stereomicroscope having a vertical objective system, a horizontal zoom system, and an eyepiece system. The zoom system consists of two systems that are juxtaposed at the same level.
The two horizontal zoom systems and the vertical objective system reduce the vertical size of the stereomicroscope and the lens diameter of the objective system. The two zoom systems are made of small lenses. This is because, compared with a single-zoom-system configuration that passes two light fluxes through peripheral parts of each lens, the two-zoom-system configuration passes two light fluxes through the centers of respective lenses. To achieve the same magnification, the two-zoom-system configuration needs a shorter distance between two light fluxes (i.e., the two zoom systems) than the single-zoom-system configuration. As a result, the two-zoom-system configuration can employ small lenses, and in addition, reduce the lens diameter of the objective system arranged in the vicinity of the zoom systems, thereby reducing the size of the inlet opening for receiving light from a target. Consequently, the stereomicroscope of the first aspect is horizontally slim to allow a doctor to easily observe a target under the stereomicroscope with the naked eye when the doctor shifts his or her eyes from the eyepieces of the stereomicroscope.
According to the first aspect; the vertical objective system directly receives vertically scattered light from a target. The objective system needs no additional optical element to bend an optical axis, and therefore, the length of an optical path from a target to the objective system can be shortened. This secures a wide view area at low magnification even with a small inlet opening. The stereomicroscope of the first aspect, therefore, is compact, involves a reduced number of parts, and is simple in structure around the inlet opening thereof.
A second aspect of the present invention provides a stereomicroscope having an objective system, a zoom system, an eyepiece system, and an assistant microscope. The stereomicroscope has an inlet opening to receive a flux of light from a target, and the assistant microscope is attachable to and detachable from the inlet opening from a target side.
The assistant microscope is detached from the stereomicroscope if not needed, so that an observer may secure a wide view around the stereomicroscope when the observer sees a target under the stereomicroscope with the naked eye. The assistant microscope is attached to the inlet opening of the stereomicroscope. When the assistant microscope is detached from the stereomicroscope, the inlet opening is open to a target and the stereomicroscope completely works by itself without the assistant microscope so that an observer may observe the target with the stereomicroscope alone. The assistant microscope has optical systems that are independent of those of the stereomicroscope, and therefore, the magnification of the assistant microscope is adjustable separately from the stereomicroscope. This makes combinational surgery easier. For example, a main doctor may use the stereomicroscope to operate on a deep part of a target while an assistant doctor uses the assistant microscope to operate on a shallow part of the target.
Other and further objects and features of the present invention will become obvious upon an understanding of the illustrative embodiments about to be described in connection with the accompanying drawings or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employing of the invention in practice.